720ppm of Ca?!!!!

[Delphinus]

Jon - If nothing is using up the Ca then it can accumulate. Are you using tap water? Our water is very high in carbonates so it is pretty easy to get a pretty high Ca reading.

If Alk is low then even if you have stuff that can use up the Ca, nothing will be able to. Thus I find it more important to dose my buffer soln over dosing my Ca soln (although by dosing the Alk I do have to dose the Ca in order to keep it near NSW levels).

Ah, one day I'll get me a Ca/Rx. One day...